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MULTIPLE AIRPORT SYSTEMS IN THE UNITED STATES: CURRENT STATUS AND FUTURE PROSPECTS

This study examines existing multiple airport systems (MASs) in the United States and assesses the prospects for new MASs in the future. Using FAA and other data, we identify 14 MAS regions in the United States, which account for 2.8% of all communities with commercial air service and 43% of total enplaned passengers. The 14 MASs divide into roughly five clusters, based on their market size, and the concentration of traffic within them. Twelve of the MAS regions are "hubs" as defined by the FAA, whereas the others are MASs because of exceptional circumstances. Analyzing the 11 "large" and "medium" hub MASs, we model concentration, as measured by the Herfindahl concentration index, and find that it decreases with regional origin and destination (O&D) traffic and increases with connecting traffic. Next we use a binary logit model to find determinants of MAS status. We find that the probability of a region being served by a MAS increases with the total traffic in the region, with some evidence that the probability decreases with the ratio of total enplanements to O&D traffic. Using the two models and FAA forecasts for the year 2000, we find that 13 regions currently served by a single airport have a significant MAS probability, and that about half of these are likely to be fairly unconcentrated MASs. We conclude that the U.S. air transport system has reached the point in which MASs could become increasingly common, and in which airports could, therefore, become a competitive industry in many regions.